负载均衡是用于解决一台机器(一个进程)无法解决所有请求而产生的一种算法。

Load balancing Sink Processor能够实现load balance功能，如下图Agent1是一个路由节点，负责将Channel暂存的Event均衡到对应的多个Sink组件上，而每个Sink组件分别连接到一个独立的Agent上，示例配置，如下所示：

具体配置内容：

a1.sinkgroups = g1
a1.sinkgroups.g1.sinks = k1 k2 k3
a1.sinkgroups.g1.processor.type = load_balance
#如果开启，则将失败的sink放入黑名单
a1.sinkgroups.g1.processor.backoff = true  
# 另外还支持random
a1.sinkgroups.g1.processor.selector = round_robin  
 #在黑名单放置的超时时间，超时结束时，若仍然无法接收，则超时时间呈指数增长
a1.sinkgroups.g1.processor.selector.maxTimeOut=10000

Failover Sink Processor能够实现failover功能，具体流程类似load balance，但是内部处理机制与load balance完全不同。

Failover Sink Processor维护一个优先级Sink组件列表，只要有一个Sink组件可用，Event就被传递到下一个组件。故障转移机制的作用是将失败的Sink降级到一个池，在这些池中它们被分配一个冷却时间，随着故障的连续，在重试之前冷却时间增加。一旦Sink成功发送一个事件，它将恢复到活动池。 Sink具有与之相关的优先级，数量越大，优先级越高。

例如，具有优先级为100的sink在优先级为80的Sink之前被激活。如果在发送事件时汇聚失败，则接下来将尝试下一个具有最高优先级的Sink发送事件。

如果没有指定优先级，则根据在配置中指定Sink的顺序来确定优先级。
示例配置如下所示：

a1.sinkgroups = g1
a1.sinkgroups.g1.sinks = k1 k2 k3
a1.sinkgroups.g1.processor.type = failover
#优先级值, 绝对值越大表示优先级越高
a1.sinkgroups.g1.processor.priority.k1 = 5  
a1.sinkgroups.g1.processor.priority.k2 = 7
a1.sinkgroups.g1.processor.priority.k3 = 6
#失败的Sink的最大回退期（millis）
a1.sinkgroups.g1.processor.maxpenalty = 20000  

• flume串联跨网络传输数据

  • avro sink

  • avro source

    使用上述两个组件指定绑定的端口ip 就可以满足数据跨网络的传递 通常用于flume串联架构中

一 ： 负载准备

将node01上的flume，拷贝到另外两台机器上：

scp -r /export/servers/flume1.8.0/ node02:/export/servers/
scp -r /export/servers/flume1.8.0/ node03:/export/servers/

1 配置文件准备

node01 配置内容为：

在flume的conf目录：

vim exec-avro.conf

添加：

#agent1 name
agent1.channels = c1
agent1.sources = r1
agent1.sinks = k1 k2

#set gruop
agent1.sinkgroups = g1

#set channel
agent1.channels.c1.type = memory
agent1.channels.c1.capacity = 1000
agent1.channels.c1.transactionCapacity = 100

agent1.sources.r1.channels = c1
agent1.sources.r1.type = exec
agent1.sources.r1.command = tail -F /root/logs/123.log

# set sink1
agent1.sinks.k1.channel = c1
agent1.sinks.k1.type = avro
agent1.sinks.k1.hostname = node02
agent1.sinks.k1.port = 52020

# set sink2
agent1.sinks.k2.channel = c1
agent1.sinks.k2.type = avro
agent1.sinks.k2.hostname = node03
agent1.sinks.k2.port = 52020

#set sink group
agent1.sinkgroups.g1.sinks = k1 k2

#set failover
agent1.sinkgroups.g1.processor.type = load_balance
agent1.sinkgroups.g1.processor.backoff = true
agent1.sinkgroups.g1.processor.selector = round_robin
agent1.sinkgroups.g1.processor.selector.maxTimeOut=10000

node02 配置内容为：

在flume的conf目录：

# Name the components on this agent
a1.sources = r1
a1.sinks = k1
a1.channels = c1

# Describe/configure the source
a1.sources.r1.type = avro
a1.sources.r1.channels = c1
a1.sources.r1.bind = node02
a1.sources.r1.port = 52020

# Describe the sink
a1.sinks.k1.type = logger

# Use a channel which buffers events in memory
a1.channels.c1.type = memory
a1.channels.c1.capacity = 1000
a1.channels.c1.transactionCapacity = 100

# Bind the source and sink to the channel
a1.sources.r1.channels = c1
a1.sinks.k1.channel = c1

node03 配置内容为：

在flume的conf目录：

vim avro-logger.conf

添加：

# Name the components on this agent
a1.sources = r1
a1.sinks = k1
a1.channels = c1

# Describe/configure the source
a1.sources.r1.type = avro
a1.sources.r1.channels = c1
a1.sources.r1.bind = node03
a1.sources.r1.port = 52020

# Describe the sink
a1.sinks.k1.type = logger

# Use a channel which buffers events in memory
a1.channels.c1.type = memory
a1.channels.c1.capacity = 1000
a1.channels.c1.transactionCapacity = 100

# Bind the source and sink to the channel
a1.sources.r1.channels = c1
a1.sinks.k1.channel = c1

2 启动

从第三台开始：

node03上执行：

bin/flume-ng agent -c conf -f conf/avro-logger.conf -n a1 -Dflume.root.logger=INFO,console

node02上执行：

bin/flume-ng agent -c conf -f conf/avro-logger.conf -n a1 -Dflume.root.logger=INFO,console

node01上执行：

bin/flume-ng agent -c conf -f conf/exec-avro.conf -n agent1 -Dflume.root.logger=INFO,console

node02,node03 对接上了 node01！！

3 测试

tail -F /root/logs/456.log

根据上面的配置可得，这里是监控 456.log的文件的，所以动态写入：

#!/bin/bash
while true
do
 date >> /export/servers/taillogs/access_log;
  sleep 0.5;
done

可以看到， 在node02 和 node03 进行串联！！

二 容错 测试

2 配置文件准备

node01 配置内容为：

在flume的conf目录：

vim exec-avro.conf

添加：

#agent1 name
agent1.channels = c1
agent1.sources = r1
agent1.sinks = k1 k2

#set gruop
agent1.sinkgroups = g1

#set channel
agent1.channels.c1.type = memory
agent1.channels.c1.capacity = 1000
agent1.channels.c1.transactionCapacity = 100

agent1.sources.r1.channels = c1
agent1.sources.r1.type = exec
agent1.sources.r1.command = tail -F /root/logs/456.log

# set sink1
agent1.sinks.k1.channel = c1
agent1.sinks.k1.type = avro
agent1.sinks.k1.hostname = node02
agent1.sinks.k1.port = 52020

# set sink2
agent1.sinks.k2.channel = c1
agent1.sinks.k2.type = avro
agent1.sinks.k2.hostname = node03
agent1.sinks.k2.port = 52020

#set sink group
agent1.sinkgroups.g1.sinks = k1 k2

#set failover
agent1.sinkgroups.g1.processor.type = failover
agent1.sinkgroups.g1.processor.priority.k1 = 10
agent1.sinkgroups.g1.processor.priority.k2 = 1
agent1.sinkgroups.g1.processor.maxpenalty = 10000

node02 配置内容为：

在flume的conf目录：

vim avro-logger.conf

添加：

# Name the components on this agent
a1.sources = r1
a1.sinks = k1
a1.channels = c1

# Describe/configure the source
a1.sources.r1.type = avro
a1.sources.r1.channels = c1
a1.sources.r1.bind = node02
a1.sources.r1.port = 52020

# Describe the sink
a1.sinks.k1.type = logger

# Use a channel which buffers events in memory
a1.channels.c1.type = memory
a1.channels.c1.capacity = 1000
a1.channels.c1.transactionCapacity = 100

# Bind the source and sink to the channel
a1.sources.r1.channels = c1
a1.sinks.k1.channel = c1

node03 配置内容为：

在flume的conf目录：

vim avro-logger.conf

添加：

# Name the components on this agent
a1.sources = r1
a1.sinks = k1
a1.channels = c1

# Describe/configure the source
a1.sources.r1.type = avro
a1.sources.r1.channels = c1
a1.sources.r1.bind = node03
a1.sources.r1.port = 52020

# Describe the sink
a1.sinks.k1.type = logger

# Use a channel which buffers events in memory
a1.channels.c1.type = memory
a1.channels.c1.capacity = 1000
a1.channels.c1.transactionCapacity = 100

# Bind the source and sink to the channel
a1.sources.r1.channels = c1
a1.sinks.k1.channel = c1

3 启动

从第三台开始：

node03上执行：

bin/flume-ng agent -c conf -f conf/avro-logger.conf -n a1 -Dflume.root.logger=INFO,console

node02上执行：

bin/flume-ng agent -c conf -f conf/avro-logger.conf -n a1 -Dflume.root.logger=INFO,console

node01上执行：

bin/flume-ng agent -c conf -f conf/exec-avro.conf -n agent1 -Dflume.root.logger=INFO,console

4 测试

目前只有node02在跑，当node02暂停的时候，node03开始跑了！！